1. Field of the Invention
The present invention relates to an adaptive equalizing device used in a mobile communication.
2. Description of the Related Art
With the progress of communication technologies, a high speed data transmission has been required in the mobile communication. In a radio communication where a data transfer rate is more than several Mbps, multipath propagation generates, resulting in a deterioration of a communication quality. To prevent the deterioration, an adaptive equalizer is provided in a radio transmission/reception apparatus.
FIG.1 is used to explain a configuration of a conventional filter bank used in an adaptive equalizer. The filter bank is primarily composed of a splitting section for splitting an input signal into M frequency bands and a synthesizing section for rearranging split signals to reconstruct an original signal.
The splitting section is composed of analysis filter 1 and sampling rate converter 2. Analysis filter 1 is composed of M analysis filters Hi (z) with different filter coefficients to split the input signal into M frequency bands. A split signal is downsampled at a sampling rate of 1/M times in sampling rate converter 2 provided behind each analysis filter 1.
The signal is upsampled at a sampling rate of M times in sampling rate converter 3, then reconstructed into the original signal by synthesis filter 4. This synthesis filter 4 is composed of M analysis filters Gi(z) with different filter coefficients.
The input signal is split into M frequency bands by the analysis filter 1 and sampling rate converter 2 and will be output ideally as showed in FIG. 2.
However, since the above-mentioned conventional filter bank can not reconstruct split signals properly when a distortion generates in split signals, there is a problem that the conventional filter bank is not applicable to the mobile communication in which a fading distortion and so on occur.
It is an object of the present invention to provide an adaptive equalizing device capable of compensating a distortion fraction of each band split signal and of reconstructing split signals properly by a filter bank.
The object is achieved by the adaptive equalizing device capable of performing training processing based on a known training signal received in advance to obtain a distortion degree of a signal, compensating the distortion fraction of the signal, and reconstructing the split signals properly by the filter bank.